scholarly journals Homogeneous electrocatalytic oxidation of ammonia to N2 under mild conditions

2019 ◽  
Vol 116 (8) ◽  
pp. 2849-2853 ◽  
Author(s):  
Faezeh Habibzadeh ◽  
Susanne L. Miller ◽  
Thomas W. Hamann ◽  
Milton R. Smith

We report that ruthenium polypyridyl complexes can catalyze ammonia oxidation to dinitrogen at room temperature and ambient pressure. During bulk electrolysis experiments, gas chromatography and mass spectrometry analysis of the headspace in the electrochemical cell showed that dinitrogen and dihydrogen are generated from ammonia with high faradaic efficiencies. A proposed mechanism where a hydrazine complex is the initial N–N bonded intermediate is supported by chemical and electrochemical experiments. This is a well-defined system for homogeneous electrocatalytic ammonia oxidation. It establishes a platform for answering mechanistic questions relevant to using ammonia to store and distribute renewable energy.

RSC Advances ◽  
2020 ◽  
Vol 10 (24) ◽  
pp. 14099-14106
Author(s):  
Hashem Shahroosvand ◽  
Leyla Heydari ◽  
Babak Nemati Bideh ◽  
Babak Pashaei

Electroplex emission is rarely seen in ruthenium polypyridyl complexes, and there have been no reports from light-emitting electrochemical cells (LECs) to date. Here, near-infrared (NIR) emission via the electroplex mechanism in a LEC was reported.


Foods ◽  
2021 ◽  
Vol 10 (9) ◽  
pp. 2183
Author(s):  
Cláudia P. Passos ◽  
Sílvia Petronilho ◽  
António F. Serôdio ◽  
Andreia C. M. Neto ◽  
Dylan Torres ◽  
...  

Acrylamide (AA) is a food contaminant in thermally processed products that is object of tight control. A simple and easy-to-apply methodology for routine monitoring of AA levels in food products could allow producers to be players in the control of their own products. In this work, a simple methodology for AA quantification without derivatization was developed for biscuits, for which the benchmark levels recommended by EFSA are 350 µg/kg, and 150 µg/kg for biscuits for infants and young children. Headspace-solid phase microextraction (HS-SPME) was used in 120 mL screwed-cap vials with a carboxen/polydimetylsiloxane fiber, 4 g of biscuits, and 10 mL of water during 15 min at room temperature under stirring. The addition of 30 mL of propanol under stirring during 15 min at room temperature and 15 min at 60 °C was used to promote AA transfer to the headspace. The fiber exposure was 45 min. A gas chromatography-mass spectrometry analysis allowed to obtain an external calibration curve at m/z 71, with linearity R2 > 0.99 and precision RSD < 9%. The detection and quantification limits were 27.4 µg/kg and 91.5 µg/kg, respectively. The methodology was successfully used in biscuits with lower AA amount, where mitigation strategies (asparaginase or pectate) were applied.


The Analyst ◽  
2021 ◽  
Author(s):  
Tomos E. Morgan ◽  
Craig Jakes ◽  
Hendrik-Jan Brouwer ◽  
Silvia Millán-Martín ◽  
Jean-Pierre Chervet ◽  
...  

Complete inline reduction of NISTmAb disulfide bonds using an electrochemical cell coupled to LC-MS analysis, reduction is carried out without the use of traditional reducing agents or enzymes.


2017 ◽  
Vol 70 (4) ◽  
Author(s):  
Jack T Seki ◽  
Andrea Bozovic ◽  
Roy Lee ◽  
Rita Kwong ◽  
Eshetu G Atenafu ◽  
...  

<p><strong>ABSTRACT</strong></p><p><strong>Background:</strong> The addition of the immunostimulant plerixafor to the current standard-of-care regimens of granulocyte colony-stimulating growth factor with or without chemotherapy has improved clinical results in terms of successful stem cell mobilization and the outcomes of stem cell transplant in various settings. With this medical innovation has come an added financial cost for institutions where stem cell transplants are routinely performed, and there may be a further financial burden when the contents of partial vials of the drug are wasted, given that plerixafor<br />vials (Mozobil, Sanofi-Aventis Canada Inc) are currently deemed suitable only for single use.</p><p><strong>Objective:</strong> To determine whether the portion of plerixafor remaining in an opened vial of the Mozobil product after administration of a single dose is chemically stable, by comparison with the original product.</p><p><strong>Methods:</strong> Stability testing of partial drug contents of an opened vial, stored at room temperature or under refrigeration (4°C), was conducted using liquid chromatography–tandem mass spectrometry analysis. The mean concentration of plerixafor (μmol/L), standard deviation, coefficient of variation, and bias were determined on days 2, 3, 11, 17, 24, and 31. Method validation included determination of precision, sensitivity, recovery, dilution linearity, and carryover.</p><p><strong>Results:</strong> Throughout the 4-week testing period, measured plerixafor concentration in aliquots stored at room temperature and under refrigeration, tested in series over time, appeared similar. The mean residual drug concentration after initial opening was slightly, but not significantly, higher for the sample designated for storage at room temperature than the one designated for refrigerated storage (40.4 versus 39.9 μmol/L; p = 0.37).</p><p><strong>Conclusions:</strong> Residual plerixafor after initial opening of a vial of the Mozobil product remained chemically stable for at least 2 weeks both at room temperature and under refrigeration. The results of this study provide in vitro evidence to support multiple uses, instead of single use, of vials of this drug in an aseptic, controlled environment.</p><p><strong>RÉSUMÉ</strong></p><p><strong>Contexte :</strong> L’ajout de l’immunostimulant plérixafor aux traitements reconnus comme la norme de soins actuelle quant au facteur de stimulation des colonies de granulocytes, accompagné ou non de chimiothérapie, a amélioré les résultats cliniques de mobilisation des cellules souches et les résultats de greffe de cellules souches dans différents contextes. Cela dit, avec cette innovation médicale vient un poids financier supplémentaire pour les établissements où l’on exécute couramment des greffes de cellules souches. En outre, comme les fioles de plérixafor (Mozobil, Sanofi-Aventis Canada Inc.) sont présentement jugées adéquates pour un usage unique seulement, l’excédent de médicament gaspillé peut représenter une dépense additionnelle.</p><p><strong>Objectif :</strong> Déterminer si ce qui reste de Mozobil dans une fiole ouverte après l’administration d’une dose unique est chimiquement stable comparativement au produit de départ.</p><p><strong>Méthodes :</strong> Une étude de stabilité du contenu partiel d’une fiole de médicament ouverte, entreposé à température ambiante ou conservé au réfrigérateur (4°C), a été réalisée par chromatographie en phase liquide couplée à la spectrométrie de masse en tandem. La concentration moyenne de plérixafor (μmol/L), l’écart-type, le coefficient de variation et le biais ont été établis aux jours 2, 3, 11, 17, 24 et 31. La méthode de validation comprenait la détermination de : la précision, la sensibilité, la récupération, la limite de linéarité et la contamination inter-échantillons.</p><p><strong>Résultats :</strong> Tout au long des quatre semaines d’analyse, les concentrations mesurées des aliquotes de plérixafor, entreposées à température ambiante ou conservées au réfrigérateur et analysées en séries chronologiques, semblaient similaires. Les concentrations moyennes de médicament restant après l’ouverture initiale étaient légèrement plus élevées lorsqu’entreposées à température ambiante (40,4 μmol/L) que lorsque réfrigérées (39,9 μmol/L) (p = 0,37), mais pas de façon significative.</p><p><strong>Conclusions :</strong> Le plérixafor résiduel, après l’ouverture initiale des fioles de Mozobil, demeurait chimiquement stable pendant au moins deux semaines, qu’il soit entreposé à température ambiante ou conservé au réfrigérateur. Les résultats de la présente étude offrent des données in vitro qui soutiennent une utilisation multiple, plutôt qu’un usage unique, des fioles de ce médicament en milieu aseptique contrôlé.</p>


2022 ◽  
Vol 34 (2) ◽  
pp. 402-408
Author(s):  
B.V. Narasimha Raju Katari ◽  
Vemula Madhu ◽  
Annapurna Nowduri ◽  
Muralidharan Kaliyaperumal ◽  
Chidananda Swamy Rumalla

Bisphenols are important endocrine disruptors, which were widely used in the variety of food packing and storage materials which often come into contact with various food products packed in them. The presence of bisphenols in water is harmful for the health of humans as well as aquatic animals and also, they accumulate over a period of time. Hence, the present work aimed to develop a simple and accurate GCMS-SIM method for the quantification of bisphenols in packaged drinking water as well as the water samples collected in river and lakes in Andhra Pradesh state of India. Bisphenols were extracted by simple solvent extraction with acetonitrile and silylated by N,O-bis (trimethylsilyl)trifluoro acetamide and analyzed by GC-MS. Various parameters that affect the recovery of the analytes were carefully optimized and the developed method was validated. The recoveries of the analytes were in the range of 80-120 % with quantification limit of 1 ng/L. The calibration curve was linear in the concentration range of 5 ng/L to 10 μg/L. The method was applied for the quantification of bisphenols in packaged drinking water at room temperature and at 50 ºC at various time intervals. The results proved that the water sample kept at room temperature doesn’t shows peaks corresponding to bisphenols. The water sample exposed to 50 ºC for 30 days bisphenols content 10, 12, 22 and 8 ng/L respectively for bisphenol G (BPG), bisphenol F (BPF), bisphenol E, (BPE) and bisphenol A (BPA) whereas the same sample at 180 days of exposer shows 60, 51, 61 and 22 ng/L respectively confirms that the leaching of plastic due to temperature increases the bisphenols level. Among the real time samples studied, the bisphenols level was observed to be very high in Kolleru Lake and it is having 17, 14, 8 and 12 ng/L of BPG, BPF, BPE and BPA, respectively confirms that due to high plastic pollution the bisphenols level was high in these samples. Hence, it can be concluded that the method can be suitable for the analysis of bisphenols in drinking water as well as in wastewater samples.


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